US5973780A - Echelle spectroscope - Google Patents

Echelle spectroscope Download PDF

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Publication number
US5973780A
US5973780A US09/226,707 US22670799A US5973780A US 5973780 A US5973780 A US 5973780A US 22670799 A US22670799 A US 22670799A US 5973780 A US5973780 A US 5973780A
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Prior art keywords
echelle
spectroscope
ranges
spectral light
image detector
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US09/226,707
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Naohiro Tsuboi
Fumikazu Oogishi
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Shimadzu Corp
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Shimadzu Corp
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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01J—MEASUREMENT OF INTENSITY, VELOCITY, SPECTRAL CONTENT, POLARISATION, PHASE OR PULSE CHARACTERISTICS OF INFRARED, VISIBLE OR ULTRAVIOLET LIGHT; COLORIMETRY; RADIATION PYROMETRY
    • G01J3/00—Spectrometry; Spectrophotometry; Monochromators; Measuring colours
    • G01J3/12—Generating the spectrum; Monochromators
    • G01J3/18—Generating the spectrum; Monochromators using diffraction elements, e.g. grating
    • G01J3/24—Generating the spectrum; Monochromators using diffraction elements, e.g. grating using gratings profiled to favour a specific order
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01J—MEASUREMENT OF INTENSITY, VELOCITY, SPECTRAL CONTENT, POLARISATION, PHASE OR PULSE CHARACTERISTICS OF INFRARED, VISIBLE OR ULTRAVIOLET LIGHT; COLORIMETRY; RADIATION PYROMETRY
    • G01J3/00—Spectrometry; Spectrophotometry; Monochromators; Measuring colours
    • G01J3/12—Generating the spectrum; Monochromators
    • G01J3/18—Generating the spectrum; Monochromators using diffraction elements, e.g. grating

Definitions

  • This invention relates to spectroscopes which are used in different kinds of apparatus for spectral analyses such as emission and absorption spectral analyses.
  • this invention relates to echelle spectroscopes which make use of an echelle diffraction grating.
  • Echelle diffraction gratings for use as a light-dispersing element for an echelle spectroscope are conventionally designed so as to have a larger blaze angle ⁇ than ordinary echelle diffraction gratings, their free spectral range being shorter on the short-wavelength side and longer on the long-wavelength side so as to provide high dispersion and high resolving power.
  • an image detector comprising a CCD or an array of photo-diodes as a light detector for detecting spectral light dispersed by a diffraction grating because the spectral light of each wavelength is detected in units of pixels and hence the structure of the light detector can be made simpler than if a conventional photo-multiplier or the like is used for the detection of light.
  • FIG. 6 shows an example of conventional echelle spectroscope comprised as a combination of an echelle diffraction grating and an image detector having such characteristics according to the so-called Czerny-Turner type arrangement.
  • Light from a source 1 is passed through an entrance slit 2 and is directed to an echelle diffraction grating 4 after it is made into a parallel beam by means of a collimation mirror 3. Since the dispersed light from the echelle diffraction grating 4 includes overlapping among spectral light portions of different orders, it is further dispersed by a separating element 7 into these spectral light portions of different orders in a direction perpendicular to the dispersion direction by the echelle diffraction grating 4. The separated spectral light portions thus obtained are then reflected by an imaging mirror 9 such that they form images on an image detector 10.
  • An ordinary echellette grating or prism may be used as the aforementioned separating element 7.
  • the mechanism for effecting the shift is required to have the accuracy on the order of less than several ⁇ m both in the horizontal and vertical directions in order to maintain reproducibility of the position of the spectral images. This again increases the overall cost of the apparatus. Since the shifting will be by mechanical means, furthermore, there will also arise the problem of stability. If an image detector with insufficient positional accuracy is shifted back and forth in the direction of the wavelength, the result of the measurements may in reality be as shown in FIGS.
  • a plurality of optical paths are provided between the echelle diffraction grating and the element for separating dispersed spectral light into portions corresponding to different orders of diffraction (hereinafter referred to as "the separating element"), as described above with reference to FIG. 6, according to the range of wavelengths, and the optical elements such as the echelle diffraction grating are arranged such that spectral light along each optical path will form an image on a same image detector.
  • a shutter is disposed on the optical path such that only a selected optical path can be opened, depending on the range of wavelengths to be detected, while the other optical paths are closed, thereby allowing only the spectral light portion within the selected range of wavelengths forms an image on the image detector.
  • the user has only to move the shutter and to switch the optical paths for forming a different image with the spectral light portions of wavelengths in a different range but on the same image detector.
  • the correspondence is preliminarily established between selected ranges of wavelengths and detected outputs from the image detector, it is possible to carry out spectral analyses over a wide range of wavelengths even with a relatively small image detector.
  • An echelle spectroscope embodying this invention may therefore be characterized as comprising one or more echelle diffraction gratings, one or more separating elements for separating dispersed light into portions corresponding to different orders of diffraction and one or more imaging means such as imaging mirrors but there is only one image detector.
  • These components are so designed and arranged with respect to one another that the total range of wavelength to be analyzed is divided into a plurality of smaller ranges and the portions of the spectral light from a source corresponding to different ones of these divided wavelength ranges travel on separate paths but would each form an image on the same image detector.
  • a shutter is provided so as to selectively allow one of these portions of spectral light corresponding to one of the different wavelength ranges to pass therethrough.
  • FIG. 1 is a schematic drawing of the arrangement of an echelle spectroscope embodying this invention
  • FIG. 2 is an echellogram showing the spectral characteristic of the echelle spectroscope
  • FIGS. 3A, 3B and 3C are an example of measured results obtained by the spectroscope of FIG. 1 to show their reproducibility
  • FIG. 4 is a graph for showing the resolving power of the spectroscope of FIG. 1 from its measured results;
  • FIG. 5 is a schematic drawing of another echelle spectroscope embodying this invention.
  • FIG. 6 is a schematic drawing of a prior art echelle spectroscope.
  • FIGS. 7A, 7B and 7C are an example of measured results obtained by the prior art spectroscope of FIG. 6 to show their reproducibility.
  • FIG. 1 shows an echelle spectroscope embodying this invention, comprising a light source 1, an entrance slit 2, a collimation mirror 3, a single imaging mirror 9 serving as its imaging means and a single image detector 10, as described above with reference to FIG. 6.
  • This echelle spectroscope is different from the prior art spectroscope of FIG. 6 firstly in that a plurality of echelle diffraction gratings 4a and 4b and as many separating elements 7a and 7b (two each in the example illustrated in FIG. 1) are provided, corresponding to ranges of wavelengths to be covered, and secondly in that there is also a shutter 5 with a window 5a for selecting each of the ranges of wavelengths.
  • the number N of ruled lines and the blaze angle ⁇ of each of the echelle diffraction gratings 4a and 4b are determined such that specified linear dispersion and resolving power can be obtained respectively within areas L long on the longer-wavelength side and L short on the shorter-wavelength side on the echellogram shown in FIG. 2.
  • specifications of the echelle diffraction gratings 4a and 4b and the separating elements 7a and 7b are determined such that greater linear dispersion and higher resolving power can be obtained in the shorter-wavelength side than in the longer-wavelength side.
  • Table 1 shows an example of such specifications when the image detector 10 is set for the opening of 1/2 inch-angle.
  • the echelle gratings 4a and 4b, the elements 7a and 7b and the imaging mirror 9 are arranged with respect to one another in such a way that the spectral light portion with shorter wavelengths (in range L short ) from the grating 4a, made incident on element 7a and the spectral light portion with longer wavelengths (in range L long from the grating 4b, made incident on element 7b, are both reflected by the single imaging mirror and each form an image on the same image detector 10.
  • the shutter 5 is provided because, without this shutter 5 present, the spectral light portions with wavelengths in both ranges L long and L short would form mutually overlapping images all over the surface of the image detector 10.
  • the shutter 5 is disposed on a part of the optical path between the echelle diffraction gratings 4a and 4b and the separating elements 7a and 7b such that it will be shifted to a first position when shorter wavelengths (in range L short ) are being measured by allowing only the spectral light portion dispersed by the grating 4a to pass therethrough and to a second position when longer wavelengths (in range L long ) are being measured by allowing only the spectral light portion dispersed by the other grating 4b to pass therethrough.
  • numeral 6 indicates a driving mechanism including a motor and gears for moving the shutter 5 between the aforementioned two positions.
  • the echelle spectroscope With the echelle spectroscope thus structured, light from the light source 1 is passed through the entrance slit 2 and, after it is made into a parallel beam by means of the collimation mirror 3, is made incident on the echelle diffraction gratings 4a and 4b.
  • the spectral light portions dispersed by the echelle diffraction gratings 4a and 4b are directed respectively towards the elements 7a and 7b. If the spectral light portion in the shorter-wavelength range L short is to be measured, the driving mechanism 6 is activated so as to move the shutter 5 such that only the light being directed from the grating 4a to the element 7a will pass through the window 5a.
  • the driving mechanism 6 is activated so as to move the shutter 5 such that only the light being directed from the grating 4b to the element 7b will pass through the window 5a.
  • the spectral light which has passed through the window 5a is dispersed by the corresponding one of the elements 7a or 7b in a direction perpendicular to the direction of dispersion by the echelle dispersion gratings 4a and 4b, diffracted portions of light of different orders being separated.
  • the dispersed spectral light of a selected order is then reflected by the imaging mirror 9 and forms an image on the image detector 10.
  • the range of wavelengths L long or L short in the spectral light to be examined is selected according to this invention by moving the shutter 5.
  • the image detector 10 may not be able detect all at once the entire range of wavelengths which are to be analyzed, it is possible to determine by switching the position of the shutter 5 whether the output being received from the image detector corresponds to the shorter-wavelength range L short or the longer-wavelength range L long . In this manner, a result of measurement over the entire range of wavelengths (both L short and L long ) can be obtained by using the single image detector 10.
  • the image detector 10 Since the image detector 10 remains at a fixed position while only the shutter 5 is moved to switch the optical path, the positional relationship among the optical components of the spectroscope does not change. This makes it possible to obtain stable results of measurement with good reproducibility. Although the shutter 5 is moved, a same intensity value Ii is obtained corresponding to a same wavelength value ⁇ i as shown in FIGS. 3A, 3B and 3C because the image detector 10 remains at a fixed position.
  • the echelle diffraction gratings 4a and 4b and the separating elements 7a and 7b are designed such that a larger linear dispersion and a higher resolving power can be obtained in the shorter-wavelength region than in the longer-wavelength region. This makes it possible, as shown in FIG. 4 for example, to measure peaks P 1 and P 2 at the wavelengths of Cd and As separately.
  • FIG. 5 shows another echelle spectroscope embodying this invention which is different from the spectroscope described above with reference to FIG. 1 in that it uses only one echelle grating 4 and one separating element 7 but is provided with a plurality of imaging mirrors (two mirrors in the example illustrated in FIG. 5) 9a and 9b, serving as imaging means arranged such that their focal lengths f a and f b correspond to different ranges of wavelengths.
  • the focal lengths f a and f b of the two imaging mirrors 9a and 9b are determined such that these two mirrors 9a and 9b will each provide a specified linear dispersion respectively inside the short-wavelength region L short and inside the long-wavelength region L long shown in the echellogram of FIG. 2.
  • a shutter 5 with a window 5a is disposed according to this embodiment of the invention on the optical path between the single separating element 7 and the imaging mirrors 9a and 9b and is adapted to allow only spectral light with shorter wavelengths separated by the separating element 7 to pass through the window 5a when the measurement is for shorter-wavelength light and to allow only spectral light with longer wavelengths separated by the same separating element 7 to pass through the window 5a when the measurement is for longer-wavelength light.
  • the echelle grating 4, the separating element 7 and the imaging mirrors 9a and 9b, as well as their positional relationships are determined such that the spectral light portion with wavelengths in each of the wavelength ranges (L short or L long selected by the position of the shutter 5 will form an image, after reflected by the corresponding one of the imaging mirrors 9a and 9b, on the same image detector 10.
  • the structure of the spectroscope shown in FIG. 5 is identical to that described with reference to FIG. 1 and hence a detailed description will be omitted.
  • echelle spectroscope With the echelle spectroscope shown in FIG. 5, too, light from the light source 1 is passed through the entrance slit 2 and, after it is made into a parallel beam by means of the collimation mirror 3, is made incident on the echelle diffraction grating 4.
  • the spectral light dispersed by the grating 4 is directed to the separating element 7 by which it is dispersed further in a direction perpendicular to the direction of dispersion by the grating 4 into separate spectral light portions corresponding to different orders of diffraction.
  • the spectral light passing through the window 5a is reflected by the imaging mirror 9a or 9b but forms an image on the same image detector 10 without regard to which of the imaging mirrors 9a and 9b reflected it.
  • the shutter 5 may be disposed instead between the collimation mirror 3 and the echelle diffraction gratings 4a and 4b.
  • the plurality of separating elements 7a and 7b may be replaced by a single element while the orientations of the individual echelle gratings 4a and 4b are varied such that their optical relationships allow spectral light portions with wavelengths in the shorter-wavelength and longer-wavelength ranges L short and L long to each form an image on the same image detector 10.
  • the number of echelle gratings 4a and 4b in the first embodiment of the invention and the number of imaging mirrors 9a and 9b in the second embodiment of the invention need not be two, but may be further increased in order to improve the resolving power.
  • all such modifications and variations that may be apparent to a person skilled in the art are intended to be included within the scope of the invention.
  • spectral light with wavelengths over a wide range can be analyzed by means of a relatively small image detector because each spectral light portion with wavelengths within any selected one of different ranges forms an image on the same image detector.
  • the resolving power of wavelengths is improved, and analyses with a high level of accuracy become possible.
  • the image detector is no longer required to undergo a step-wise motion, as in the case of some prior art spectroscopes, the optical system is stabilized and the reproducibility of the measured results is improved.
  • the overall cost of the spectroscope can be prevented from rising.

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  • Physics & Mathematics (AREA)
  • Spectroscopy & Molecular Physics (AREA)
  • General Physics & Mathematics (AREA)
  • Spectrometry And Color Measurement (AREA)
  • Investigating Or Analysing Materials By Optical Means (AREA)
US09/226,707 1998-02-12 1999-01-07 Echelle spectroscope Expired - Fee Related US5973780A (en)

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JP10-029517 1998-02-12
JP10029517A JPH11230828A (ja) 1998-02-12 1998-02-12 エシェル分光器

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Cited By (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6304692B1 (en) 1999-09-03 2001-10-16 Zolo Technologies, Inc. Echelle grating dense wavelength division multiplexer/demultiplexer with two dimensional single channel array
US20040061860A1 (en) * 2002-09-27 2004-04-01 Fuji Photo Film Co., Ltd. Measuring method and apparatus using attenuated total reflection
US20050168738A1 (en) * 2004-02-02 2005-08-04 Akira Ohnishi Small sized wide wave-range spectroscope
FR2872571A1 (fr) * 2004-07-05 2006-01-06 Jobin Yvon Sas Soc Par Actions Dispositif optique reflecteur et dispositifs spectroscopiques comportant ces dispositifs optiques reflecteurs
US20070030484A1 (en) * 2005-08-08 2007-02-08 Acton Research Corporation Spectrograph with segmented dispersion device
US20070171416A1 (en) * 2000-11-30 2007-07-26 Tomra Systems Asa Optically controlled detection device
US20080094626A1 (en) * 2004-06-09 2008-04-24 Helmut Becker-Ross Echelle Spectometer with Improved Use of the Detector by Means of Two Spectrometer Arrangements
DE102007028505A1 (de) * 2007-06-18 2008-12-24 Gesellschaft zur Förderung angewandter Optik, Optoelektronik, Quantenelektronik und Spektroskopie e.V. Spektrometeranordnung
DE102019113478A1 (de) * 2019-05-21 2020-11-26 Analytik Jena Ag Spektrometeranordnung

Families Citing this family (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2008510964A (ja) * 2004-08-19 2008-04-10 ヘッドウォール フォトニクス，インコーポレイテッド マルチチャネル、マルチスペクトル型撮像分光計
JP4642621B2 (ja) * 2005-09-29 2011-03-02 株式会社フォトンデザイン 分光装置
CN102564591B (zh) * 2011-12-29 2014-04-16 聚光科技(杭州)股份有限公司 一种光谱分析仪和光谱分析方法
CN103981696A (zh) * 2014-05-28 2014-08-13 浙江辰鸿纺织品科技有限公司 窗帘布用的遮光折射浆
WO2016171042A1 (ja) * 2015-04-21 2016-10-27 国立大学法人香川大学 分光測定装置

Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5565983A (en) * 1995-05-26 1996-10-15 The Perkin-Elmer Corporation Optical spectrometer for detecting spectra in separate ranges

Patent Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5565983A (en) * 1995-05-26 1996-10-15 The Perkin-Elmer Corporation Optical spectrometer for detecting spectra in separate ranges

Cited By (22)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6415080B1 (en) 1999-09-03 2002-07-02 Zolo Technologies, Inc. Echelle grating dense wavelength division multiplexer/demultiplexer
US6647182B2 (en) 1999-09-03 2003-11-11 Zolo Technologies, Inc. Echelle grating dense wavelength division multiplexer/demultiplexer
US6304692B1 (en) 1999-09-03 2001-10-16 Zolo Technologies, Inc. Echelle grating dense wavelength division multiplexer/demultiplexer with two dimensional single channel array
USRE40271E1 (en) 1999-09-03 2008-04-29 Zolo Technologies, Inc. Echelle grating dense wavelength division multiplexer/demultiplexer
US20070171416A1 (en) * 2000-11-30 2007-07-26 Tomra Systems Asa Optically controlled detection device
US7701574B2 (en) 2000-11-30 2010-04-20 Tomra Systems Asa Optically controlled detection device
US20100079755A9 (en) * 2000-11-30 2010-04-01 Tomra Systems Asa Optically controlled detection device
US20040061860A1 (en) * 2002-09-27 2004-04-01 Fuji Photo Film Co., Ltd. Measuring method and apparatus using attenuated total reflection
US7057731B2 (en) * 2002-09-27 2006-06-06 Fuji Photo Film Co., Ltd. Measuring method and apparatus using attenuated total reflection
US7193707B2 (en) * 2004-02-02 2007-03-20 Ube Industries, Ltd. Small sized wide wave-range spectroscope
US20050168738A1 (en) * 2004-02-02 2005-08-04 Akira Ohnishi Small sized wide wave-range spectroscope
AU2005252809B8 (en) * 2004-06-09 2011-09-15 Leibniz - Institut fur Analytische Wissenschaften - ISAS-e.V. Echelle spectrometer with improved use of the detector by means of two spectrometer arrangements
US20080094626A1 (en) * 2004-06-09 2008-04-24 Helmut Becker-Ross Echelle Spectometer with Improved Use of the Detector by Means of Two Spectrometer Arrangements
AU2005252809B2 (en) * 2004-06-09 2011-05-19 Leibniz - Institut fur Analytische Wissenschaften - ISAS-e.V. Echelle spectrometer with improved use of the detector by means of two spectrometer arrangements
US7804593B2 (en) 2004-06-09 2010-09-28 Leibniz-Institut Fur Analytische Wissenschaften - Isas - E.V. Echelle spectometer with improved use of the detector by means of two spectrometer arrangements
FR2872571A1 (fr) * 2004-07-05 2006-01-06 Jobin Yvon Sas Soc Par Actions Dispositif optique reflecteur et dispositifs spectroscopiques comportant ces dispositifs optiques reflecteurs
US20070030484A1 (en) * 2005-08-08 2007-02-08 Acton Research Corporation Spectrograph with segmented dispersion device
US20100171953A1 (en) * 2007-06-18 2010-07-08 Gesellschaft Zur Forderung Der Analytischen Wissenschaften E.V. Spectrometer Assembly
DE102007028505A1 (de) * 2007-06-18 2008-12-24 Gesellschaft zur Förderung angewandter Optik, Optoelektronik, Quantenelektronik und Spektroskopie e.V. Spektrometeranordnung
US8102527B2 (en) 2007-06-18 2012-01-24 Leibniz-Institut fur Analytische Spectrometer assembly
DE102019113478A1 (de) * 2019-05-21 2020-11-26 Analytik Jena Ag Spektrometeranordnung
US11204277B2 (en) 2019-05-21 2021-12-21 Analytik Jena Gmbh Spectrometer arrangement

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CN1259552C (zh) 2006-06-14
JPH11230828A (ja) 1999-08-27
CN1231423A (zh) 1999-10-13

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